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Behav Brain Res. 2014 Mar 15;261:171-6. doi: 10.1016/j.bbr.2013.12.001. Epub 2013 Dec 12.

Repeated nicotine exposure during adolescence alters reward-related learning in male and female rats.

Author information

  • 1Department of Psychiatry Laboratory of Molecular Psychiatry, Yale University Ribicoff Research Facilities CMHC, 34 Park St New Haven, CT 06519, United States.
  • 2Department of Psychiatry Laboratory of Molecular Psychiatry, Yale University Ribicoff Research Facilities CMHC, 34 Park St New Haven, CT 06519, United States. Electronic address: jane.taylor@yale.edu.

Abstract

RATIONALE:

Repeated nicotine exposure causes neuroadaptations in limbic cortico-striatal circuits involved in learning and motivation. Such alterations are relevant to addiction because they are suggested to mediate the ability of smoking-associated stimuli to control behavior and to enhance nicotine-seeking and -taking behaviors. Female smokers report higher cue reactivity relative to their male counter parts, yet little is known about putative gender-specific effects of adolescent nicotine exposure on reward-related learning. Prior repeated nicotine exposure in adult male rats enhances Pavlovian approach behavior and conditioned reinforcement.

OBJECTIVE:

Given that smoking is typically initiated during adolescence, here we assessed the extent to which adolescent nicotine exposure impacts Pavlovian approach and conditioned reinforcement in male and female rats.

METHODS:

Rats were injected with nicotine on postnatal days 31-45 prior to training on Pavlovian approach behavior starting on day 51. They were trained to associate a conditioned stimulus (CS), illumination of a magazine light, and tone, with an unconditioned stimulus (US), the delivery of water, for 10-daily sessions, and then were tested on the acquisition of responding with conditioned reinforcement.

RESULTS:

Adolescent nicotine exposure selectively increased approach to the magazine during the CS in males but decreased approach to the magazine during the CS in female rats. Vehicle-exposed female rats, however, showed greater magazine approach during the CS than did male control rats. Prior nicotine exposure also enhanced conditioned reinforcement in both male and female rats.

CONCLUSIONS:

Repeated exposure to nicotine during adolescence had opposite effects on Pavlovian approach behavior in male and female rats but enhanced acquisition of a new response with conditioned reinforcement. Novel information on how nicotine exposure influences reward-related learning during adolescence may increase our understanding of neurobiological mechanisms involved in the initiation of smoking behavior.

Copyright © 2013 Elsevier B.V. All rights reserved.

KEYWORDS:

Conditioned reinforcement; Nicotine; Pavlovian approach; Reward learning; Sex differences

PMID:
24333376
[PubMed - indexed for MEDLINE]
PMCID:
PMC3953232
Free PMC Article
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